Hydraulic system



March 3, 1959 R. H. GovAN ETVAL HYDRAULIC SYSTEM 2 Sheets-Sheet 1 FiledSept. 26. 1955 ENTORS March 3, 1959 H. GOVAN ET AL HYDRAULIC SYSTEM 2Sheets-Sheet 2 Filed Sept. 26. 1955 INVENTQR fifgm/m,

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United States Patent 2,875,871 HYDRAULIC SYSTEM Roy H. Gavan, Hoboken,N. J., and Harold J. Meek, Staten Island, N. Y., assignors to JarocoEngineering Co., Hoboken, N. .l'., a corporation of New JerseyApplication September 26, 1955, Serial No."536,680

8 Claims. (Cl. 192-3) The present invention relates to a hydraulicsystem for use with vehicles. More particularly, the present inventionrelates to a hydraulic system for use in braking and acceleratingvehicles and has particular application for railway rolling stock.

Railway braking systems are necessarily designed for use in rapidlydecelerating the railway vehicles during various phases of operation andfor this purpose utilize either mechanical frictional type braking orsome form of an electrical or pneumatic braking system. A most importantfunction of the braking system is to gradually decelerate the railwaycars when bringing the railway cars to a rest position and to brake thecars at a constant rate, for example, when the cars are moving downgrade. Priorto the instant invention, the heretofore known brakingsystems were subject to considerable wear during the braking operationand the wheels of the railway cars were particularly subject to wearduring long braking periods such as on down grade runs. 1

Railway rolling "stock in addition .to having braking problems areconsiderably difiicult to start from a position "of rest due to theexcessive loads 'involved. Much anon must be expended by the prime moverto accelerate the railway cars from a position of rest'to normaloperatingsp'eed and it is seen that this acceleration period isextremely ineflicient from the point of view of fuel con- 'sumption.Moreover, if the train is moving freight, then considerably long periodsof acceleration are required to bring the train up to the normaloperating speed.

"It is therefore an object of the .present invention to provide abraking and accelerating system for use with railway rolling stock thatis adapted to eifectively brake the railway cars and, in addition, torapidly accelerate the cars from a position of rest. I

Still another object of the .present invention is to .provide ahydr'aulic braking system for use with vehicles.

Still another object of the present invention is to provide-a hydraulicsystem for use with vehicles wherein the vehicles areadapted to berapidly accelerated from-a'position of "rest.

.Still another object of the :present invention is to provide ahydraulic system for use with vehicles wherein -a remotely controlledhydraulic unit that is directly connected to the wheels of the vehicleis operated to brake or accelerate the vehicle, as desired.

Still another object of the present invention is to provide a pump unitfor use with hydraulic system for vehicle's wherein said pump isdirectly connected to the ground wheel shaft of the vehicle 'andisutilized as 'a bearingth'erefor. v

Still another object of the present invention is to 715m- 'a hydraulicsystem for braking or accelerating a land'vehicle wherein the hydraulicfluid utilized to operate the system is eifectively cooled.

Other objects and the nature and advantages of the instant inventionwill be apparent from the following ice 2 description taken inconjunction with the accompanying drawings, wherein:

Fig. 11 is a diagrammatic illustration of the hydraulic system embodiedherein and as shown has particular use with railway rolling stock;

Fig. 2 is 'a horizontal sectional view of one of the hydrauli c'unitsshown in Fig. l and is illustrated being connected directly to a wheelof a railway car; and

Fig. 3 is a view taken along the line 3-3 in Fig. 2.

Referring now to the drawings, and particularly Fig. 1, the hydraulicsystem embodied in the present invention is illustrated diagrammaticallytherein. The hydraulic system illustrated in Fig. 1 is intended for useas a braking and accelerating device and is intended to be employedinconnection with land vehicles such as, for .example, railwayrollingstock. It is understood, however, that the hydraulic system disclosedherein may be utilized in connection with other land vehicles wheneverbraking and accelerating needs are required. The apparatus illustratedin Fig. l is specifically designed for use with arailway car which isrepresented by from and rear wheel trucks generally indicated at 10 and12, respectively. The front and rear wheel trucks 1t), 12 are identicalin structure and include :frame members '14 and 16 to which is joined 'abrace 18, the brace 18 being pivotally secured to the underside of therailway car body at the pivot connection 20. Securedto the outer ends ofthe frame mem bers '14 and 16 are hydraulic units 22, each of which hasa shaft 24 extending "therein. The "hydraulic units arenormally'designed to operate as pumps but, for purposes of acceleratingthe railway car, may operate as a motor. The construction of thehydraulic units 22 will be described in detail hereinbelow.

'Aconventional railway wheel 26 is secured to the outer end of the shaft24 and engages a rail 28 for movement thereover. It is seen thatthe-conventional axle upon which the wheels 26 are normally mounted iseliminated by the present invention, thereby eliminating theconventional wheel bearings. As shown in Figs. 2 and 3, the shafts 24are-mounted for-rotation in the hydraulic units 22 and, as such,each'hydraulic unit 22 defines supporting means for its shaft 24 and theassociated Wheel 26.

As will be described in more detail hereinafter, each of the hydraulicunits 22 is provided with a fluid inlet port 39 and'a fluid outlet port32, the inlet port 30 comriiunica'ting with a fluid conduit 34 thatdirects hydraulic fluid thereto from a fluid reservoir 36. All of thehydraulic units 22 are connected in parallel relation and are thusadapted to function concurrently when operating as a braking oraccelerating device. The hydraulic fluid is adapted to be recirculatedand for this purpose each of theou'tlet ports 32 is connected to a fluidconduit 38 that communicates with the reservoir 36 through a reliefvalve 40, 'a heat exchange unit generally indicated at i2and a fluidoperated pump-fan unit 44 that directs cooling air to the heat exchangeunit 42. For purposes of acceleration, a hydraulic accumulator 46communicates with the fluid conduit 38 through a conduit '48 and thefunction of the accumulator will be described in detail below.

During'nor'mal operation of the railway car, the wheels 26 will alwaysrotate in a specific direction, depending on the direction of travel ofthe locomotive. As the shaft '24 of each hydraulic unit is rotated, therotor secured thereto is rotated. Howev'enthe hydraulic units will'nottunctio'n to deliver fluid unless asuitable control device isactuated to move the operating elements of the units to an operatingposition.

Referring now to Figs. 2 and 3 of the drawings, one of the hydraulicunits 22 is illustrated in section therein and comprises a casing 48which includes an end cover 50 and a shaft cover 52. It is understoodthat all of piston 62 therein.

I the hydraulic units 22 are similar in construction and will operateconcurrently during a braking or accelerating of the vehicle to whichthey are attached. Mounted in the end cover 50 and shaft cover 52,respectively, are body bearings 54 and 56 which receive for rotationtherein a cylinder body 58. The cylinder body 58 is connected to theshaft 24 and is rotatable therewith when the railway car Wheel 26 isrotating on the track 28. Formed in the cylinder body 58 are a pluralityof radially extending cylinders 60, each of'which receives a groovedSecured to the outer end of the pistons 62 are pairs of slippers orrollers 64 which are mounted on a pin 66, the rollers engaging anannular groove 68 formed in a floating ring assembly 70. Positioned inthe end cover 50 is a central cylindrical valve 72 that is formed withaxial parallel passages 74 and 76 that communicate with central ports,one of which is indicated at 78, the'central ports communicating withthe radial cylinders 60 formed in the cylinder body 58. Formed in thevalve 72 adjacent the outer end thereof are openings 80 and 82 thatcommunicate with an inlet passage 84 and an outlet passage 86,respectively. The

'inlet passage 84'extends into the inlet port 30 and similarly theoutlet passage extends into the outlet port 32. In order to vary thestroke of the pistons 62 and thereby control the direction of dischargeof the fluid being pumped, thefloating ring assembly 70 is movable withrespect to the cylinder body 58. The floating ring assembly 70 ismounted on bearings 88 and 90 secured in guide blocks 92 and 94,respectively, the guide blocks 92, 94 being supported by guide pins 96and 98, respectively, which extend through guides cast on the casing 48.To provide for movement of the floating ring assembly 70 with respect tothe cylinder .body 58, guide rods 100 and 102 are secured to the guideblocks 92 and 94, respectively, and have joined to the outer end thereofa cross head 104. Since the hydraulic unit 22 mustbe controlledremotely, a servo motor 105 is provided and is operatively connected tothe cross head 104 for causing movement thereof. The servo motor 105comprises a cylinder 106 which receives a piston 108 for slidingmovement therein, the pitson 108 having a piston rod 110 securedthereto. The piston rod 110 is secured to the cross head 104 and isadapted to move the cross head therewith in response to pressure exertedby a pressure fluid that is directed into the cylinder 106 through fluidconduits 112 and 114.

It is understood that the means for controlling the supply of theoperating fluid to the servo motor 105 is located at a convenientlypositioned control station. It is also understood that all of thehydraulic units 22 may be controlled independently or as a unit,depending upon the needs required. However, in the normal operation ofthe device, for either braking or accelerating, all of the hydraulicunits 22 would be concurrently controlled to operate together.

It is seen that if the floating ring assembly 70 of each hydraulic unit22 is maintained in concentric relation with the cylinder body 58, thehydraulic unit 22 will not perform any work, and the unit will bemaintained in a static condition. However, if it is desired to move thehydraulic fluid through the unit, the unit thereby effecting a pumpingaction, the floating ring assembly 70 is moved inwardly by the crosshead 104 through remote control of the servo motor 105. When thefloating ring assembly 70 moves inwardly to a position such that it iseccentric with respect to the cylinder body 58, a stroke of the pistons62 is effected upon rotation of the shaft 24 and a pumping action takesplace. The hydraulic fluid is then pumped through the inlet port 30,through the passage 76 and into the cylinder 60, from where it isdirected by relative movement of the cylinder 60 and the piston 62 intothe passage 74 for discharge through passage 86 and port 32. An increasein the eccentricity of the floating ring assembly 70 with respect to thecylinder body 58 increases the quantity of fluid pumped by the unit andthereby increases the load on the shaft 24. It is seen, therefore, thatby sufliciently loading the shaft 24 of each hydraulic unit 22, abraking effect is created that will tend to decrease the speed of thevehicle.

In the operation of the device, if it is desired to brake the vehicle,for example, when the train is proceeding down a relatively long grade,the operator of the train actuates the servo motor controls to cause thecross head 104 of each hydraulic unit to move the floating ring assembly70 in eccentric relation with respect to the cylinder body 58. The loadon the shafts 24 created by the pumping of the hydraulic fluid throughthe units then sufliciently brakes the train. A greater or lesserbraking action may be obtained by varying the eccentricity of thefloating ring assembly 70, thereby increasing or decreasing the strokeof the pistons 62.

It is understood that the braking system just described is utilizedprimarily for initiating the braking action of the vehicle and in mostinstances will be used in conjunction with conventional frictionalbraking systems. Thus, when the vehicle has been sufliciently braked bythe present system, the conventional braking system may then be employedto hold the vehicle at a rest position.

Since the hydraulic system operates in a closed circuit, the heatgenerated by the fluid passing through the relief valve 40 during thebraking operation must be dissipated and, for this purpose, the heatexchange unit 42 is provided. The hydraulic fluid exhausted from theports 32 enters the fluid conduit38 and is then pumped through therelief valve 40 to the heat exchange unit 42. Cooling fins of anyconvenient construction are provided in the heat exchange unit incontact with the conduit 38 and are adapted to reduce the temperature ofthe hydraulic fluid as it circuates through the conduit 38. Cooling airis directed to the heat exchange unit 42 by the hydraulic motor 44 whichis interposed in the fluid conduit 38 and is driven by the hydraulicfluid being pumped therethrough. A fan of any suitable design is rotatedby the motor 44 and directs air into the heat exchange unit 42. Thecooled hydraulic fluid is then pumped into the reservoir 36 forrecirculation through the system.

Although the hydraulic accumulator 46 is illustrated in the drawings andhas been described above, it is apparent that in the braking operationjust described, the accumulator is not utilized. However, when thevehicle is to be accelerated from a position of rest, the accumulator isemployedand the operation of the system using the accumulator follows: 7

During the braking operation described above, the by? draulic fluid isdirected through the conduit 48 and into theaccumulator 46, which has apiston located therein. A gas precharge introduced into the accumulatorloads the piston and determines the pressure limit of the hydraulicfluid. When the pressure limit determined by the prechargedgas isreached during the braking operation, therelief valve 40 adjusted to thepredetermined pressure opens and the hydraulic fluid is then pumpedthrough the heat exchange unit 42, motor 44 and back into the reservoir36, as described above. Assuming now that the vehicle has been broughtto a position of rest, and it is desired to begin forward movement, thenthe operator of the vehicle moves the floating ring assembly 70 of eachunit outwardly to an eccentric position, whereby each of the previouslydesignated exhaust ports 32 functions to introduce hydraulic fluid fromthe accumulator 46 into the hydraulic unit 22. Since the hydraulic fluidintroduced into the units 22 from the accumulator 46 is under pressure,it acts as a motive fluid and will cause the shaft 24 of each unit 22 tobe rapidly accelerated. The hydraulic aera or-i up to normal speed or-thesupply offluid in the accumulator is exhausted, the floating ringassembly 70 of each unit 22 is moved into concentric relation to thecylinder body 58, the stroke of the pistons 62 is reduced to 'zero, andthe units then float on the line, that is, they do not deliver fluidsince pump delivery has been reduced to zero. When it is necesary toagain brake the vehicle, the cycle of operation is repeated.

:It is seen that the hydraulic system described herein will greatlyreduce wear on the conventional braking 'systems and furthermore whenthe accumulator is-employed will aid'considerably in accelerating'thevehicle from a position of rest. Thus, the load .on the vehicleengine'is reduced, resulting in more effective control and economy ofoperation.

It will be obvious to'those skilled .in the art that various changes maybe made without departing from the spirit of the invention and thereforethe invention is not limited to what is-shown in the drawings anddescribed in the specification but only as indicated in the-appendedclaims.

What is claimed is:

1. In a hydraulic braking system for a vehicle, a plurality of wheelsmounted for rotation on said vehicle, each of said wheels having a shaftsecured for rotation therewith, each of said shafts having ahydraulically operated unit operatively connected thereto and responsiveto the rotation thereof, said shafts being mounted in dependent of eachother and responsive solely to the "rotation of the associatedwheel, afluid reservoircommunicating with said units and adapted to supplyhydraulic fluid thereto and receive hydraulic fluid therefrom,

and means for controlling the operation of said units to cause said unitto operate as a pump for pumping fluid from said reservoir, the pumpingaction of said units loading said shaft and thereby braking said wheels.

2. In a hydraulic braking system for a vehicle, a plu. rality of wheelsmounted for rotation on said vehicle, each of said wheels having a shaftsecured for rotation therewith said shafts being mounted independent ofeach other and responsive solely to the rotation of the associatedwheel, each of said wheels having a hydraulic pump unit connectedthereto and responsive to the rotation thereof independent of therotation of the other units, a fluid reservoir communicating with saidpump units for supplying hydraulic fluid thereto, and individual controlmeans associated with each of said pump units for controlling theoperation thereof, said control means being operatively connected to therotor of a unit for moving said rotor to an eccentric position withrespect to said shaft, said units thereby acting to pump fluid from saidreservoir, the pumping action of said units loading the shaft thereofand thereby braking said vehicle wheels.

3. In a hydraulic braking system for a vehicle, a plurality of wheelssecured to said vehicle, each of said wheels having a shaft secured forrotation therewith independent of the rotation of the other shafts andwheels, a hydraulic pump unit connected to each of said shafts, eachsaid shaft being responsive solely to the rotation of its associatedunit, a fluid reservoir communicating with said pump unit for supplyingfluid thereto and receiving hydraulic fluid therefrom, a heat exchangesystem interposed between the discharge of said pump unit and saidreservoir, said heat exchange system including a fan operated by thepressure of the fluid being pumped through said unit to cool said fluidprior to being introduced into said reservoir, and means for controllingthe operation of said pump unit for causing said pump unit to draw fluidfrom said reservoir, the pumping action of said pump unit loading saidshaft and thereby braking said vehicle wheel rotation therewith, 1 avhydraulic unit operativelyconnected to said shaftand responsive torotation thereof .,to:purnp a hydraulic fluid through a fluid conduitcommunicating with said unit, a fluid reservoir communicating with :said

unit for supplying hydraulic fluid jthereto, :an accumulatorcommunicating with said unit and adapted toreceive said fluid thereinduring the :pumping operation until a predetermined pressure --isreached therein, means .for regulating the pressure in said accumulator,and means operatively connected to .saidunit for controlling said unitto cause said unit to operate as a pump for pumping said fluid andthereby loading said shaft to brake said vehicle, said control meansbeing further operated -to cause said fluid under pressure =;to entersaid "unit .and thereby operate said unit as a motor when said vehicleis in a position of rest,-said vehicle thereby being accelerated duringa starting operation, said control'means including a servo motor and acontrol member operatively connected to said servo motor and said unit,said control member being responsive -to said servo motor "to controlthe operation of said unit.

5. In a hydraulic system for use with a vehicle, whee means having ashaft secured for rotation therewith, ,a

hydraulic unit operatively connected to said shaft, av

control device operatively connected to said unit and adapted to becontrolled at a station remote therefrom for controlling the'operationof'said fluid unit, said control device being actuated to cause saidunit to operate as a-pump for pumping hydraulic fluid therethrough, the

pumping action-of said unit loading said shaft and thereby braking saidWheel means, a hydraulic accumulator communicating with said unitthrough a fluid conduit, said unit directing hydraulic fluid to saidaccumulator during the braking operation until a predetermined pressureis reached therein, the hydraulic fluid under pressure being introducedinto said unit when said vehicle is in a position of rest to cause saidunit to operate as a motor and thereby accelerate said shaft, means forcontrolling the pressure on said accumulator and a hydraulic motorcommunicating with said unit through a conduit and being driven by thehydraulic fluid pumped through said unit, said hydraulic motor having afan operatively connected thereto for directing a stream of cooling airinto contact with said conduit, thereby cooling said hydraulic fluid.

6. In a hydraulic braking system for a vehicle, Wheel means secured tosaid vehicle and having a shaft secured for rotation therewith, ahydraulic pump unit connected to said shaft and responsive to therotation thereof, a fluid reservoir communicating with said pump unitfor supplying fluid thereto and receiving hydraulic fluid therefrom, aheat exchange system interposed between the discharge of said pump unitand said reservoir, said heat exchange system including a fan operatedby the pressure of the fluid being pumped through said unit to cool saidfluid prior to being introduced into said reservoir, means forcontrolling the operation of said pump unit for causing said pump unitto draw fluid from said reservoir, the pumping action of said pump unitloading said shaft and thereby braking said vehicle wheel means, and ahydraulic accumulator operatively connected to said pump unit, saidaccumulator receiving said fluid from said pump unit during the brakingaction and accumulating said fluid therein until a predeterminedpressure has been reached, said control means controlling the operationof said pump unit to direct fluid under pressure through said pump unitafter said vehicle has been braked to a stationary position to operatesaid unit as a motor, thereby accelerating said wheel means from thestationary position, and means associated with said accumulator forcontrolling the pressure therein.

7. In a hydraulic system for use with a land vehicle,

wheel means adapted to be rotated by said vehicle and having a shaftsecured thereto for rotation therewith, a hydraulic unit including acylinder body secured to sa d shaft for rotation therewith, saidcylinder body including a plurality of radial cylinders, each of saidcylinders receiving a piston therein, a floating ring assembly engagingsaid pistons, and control means secured to said floating ring assemblyfor moving said floating ring assembly in eccentric relation withrespect to said cylinder body for defining a stroke for said pistons andcausing said unit to operate as a pump for pumping hydraulic fluidtherethrough, the pumping action of said unit loading said shaft andthereby braking said wheel means, said control means including a servomotor and a cross bar operatively connected to said servo motor, saidcross bar 'being secured to said floating ring assembly and responsiveto movement of said servo motor for moving said floating ring assembly,a hydraulic accumulator communicating with said unit through a fluidconduit, said unit directing hydraulic fluid to said accumulator duringthe braking operation until a predetermined pressure is reached therein,said control means controlling said hydraulic unit for introducing thehydraulic fluid under pressure therein when said vehicle'is in aposition of rest to cause said unit to operate as a motor and therebyaccelerate said shaft, and means associated with said accumulator forcontrolling the pressure therein.

8.- In a hydraulic system for use with a land vehicle, wheel meansadapted to be rotated by said vehicle and having a shaft secured theretofor rotation therewith, a hydraulic unit including a cylinder bodysecured to said shaft for rotation therewith, said cylinder bodyincluding a plurality of radial cylinders, each of said cylindersreceiving a piston therein, a floating ring assembly engaging saidpistons, and control means secured to said floating ring assembly formoving said floating ring as sembly in eccentric relation with respectto said cylinder body for defining a stroke for said pistons and causingsaid unit to operate as a pump for pumping hydraulic fluid therethrough,the pumping action of said unit loading said shaft and thereby brakingsaid wheel means, said control means including a servo motor and acrossbar operatively connected to said servo motor, said cross bar beingsecured to said floating ring assembly and responsive to movement ofsaid servo motor. for moving said floating ring assembly, a hydraulicmotor communicating with said unit through a conduit and being driven bythe hydraulic fluid pumped through said unit, a fan operativelyconnected to said hydraulic motor for directing a stream of cooling airinto contact with said con" duit thereby cooling said hydraulic fluid.

References Cited in the file of this patent UNITED STATES PATENTS1,649,347 Hardt Nov. 15, 1927 2,255,292 Lincoln Sept. 9, 1941 2,290,932Aikman July 28, 1942 2,355,604 Rupp Aug. 5, 1944 2,416,638 Morton Feb.25, 1947 2,548,919 Stevens et a1 Apr. 17, 1951 2,692,759 Swenson et a1.Oct. 26, 1954 2,772,755 Nallinger et al Dec. 4, 1956

